1. Field of the Invention
The present invention relates to a dipped cord and a radial tire, in particular a dipped cord using a hybrid cord and a radial tire using the same.
2. Background of the Invention
The conventional radial tire has been constructed with a carcass ply around that a rubber is reinforced with a fabric cord such as polyester or rayon and a belt structure that a rubber is reinforced with steel cord. And, also, for preventing the tire from deviating from the rim and for keeping stability a bead-wire is reinforced at the place where the tire contacts the rim, and the bead-wire also plays a role to fix the carcass ply.
In case of original pneumatic radial tire, a canvas sheet made from cotton has been used as carcass material, and as synthetic fabric develops some fabric such as rayon, nylon and polyester is utilized for carcass ply material, and lately a steel cord is partly utilized
Generally, for the carcass-ply material of pneumatic radial tire, in particular carcass ply material of pneumatic radial tire having aspect ratio of 0.65 to 0.82, polyester is generally used, and for the reinforced-material of the carcass ply of the pneumatic radial tire having relatively low aspect ratio, in particular lower than 0.6 for use at high speed, rayon is commonly utilized. Lately in case of this radial tire with low aspect ratio for use at high speed polyester is partly used, but the application of polyester is limited because of worse physical quality and shape stability at high temperature.
Lately in order to solve this problem, polyethylenenaphthalate which has better physical property and shape stability than polyethyleneterephthalate is partly utilized, but the application of polyethylenenaphthalate is constrained owing to the fact that in spite of better strength the adhesion to rubber is worse compared with rayon.
In case of lyocell, the adhesion of lyocell to rubber is better than that of fabrics from polyesters and the elasticity of lyocell is superior to that of rayon, but disadvantageously the fatigue resistance of lyocell is worse than that of rayon. Even though rayon fabric which is superior to lyocell in elongation is used, rayon fabric has disadvantage that the humidity elasticity of rayon fabric is relatively low.